Federal Aviation Administration, DOT.
Notice of proposed rulemaking (NPRM).
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Boeing Model 747-200C and -200F series airplanes. This proposal would require repetitive inspections to find fatigue cracking in the upper chord of the upper deck floor beams, and repair if necessary. For certain airplanes, this proposal would also provide for an optional repair/modification, which would extend certain repetitive inspection intervals. This action is necessary to find and fix cracking in certain upper deck floor beams. Such cracking could extend and sever floor beams adjacent to the body frame and could result in rapid decompression and consequent loss of controllability of the airplane. This action is intended to address the identified unsafe condition.
Comments must be received by September 8, 2003.
Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2001-NM-278-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9 a.m. and 3 p.m., Monday through Friday, except Federal holidays. Comments may be submitted via fax to (425) 227-1232. Comments may also be sent via the Internet using the following address: firstname.lastname@example.org. Comments sent via fax or the Internet must contain “Docket No. 2001-NM-278-AD” in the subject line and need not be submitted in triplicate. Comments sent via the Internet as attached electronic files must be formatted in Microsoft Word 97 or 2000 or ASCII text.
The service information referenced in the proposed rule may be obtained from Boeing Commercial Airplane Group, PO Box 3707, Seattle, Washington 98124-2207. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington.Start Further Info
FOR FURTHER INFORMATION CONTACT:
Rick Kawaguchi, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 917-6434; fax (425) 917-6590.End Further Info End Preamble Start Supplemental Information
Interested persons are invited to participate in the making of the proposed rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this action may be changed in light of the comments received.
Submit comments using the following format:
- Organize comments issue-by-issue. For example, discuss a request to change the compliance time and a Start Printed Page 43689request to change the service bulletin reference as two separate issues.
- For each issue, state what specific change to the proposed AD is being requested.
- Include justification (e.g., reasons or data) for each request.
Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket.
Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this action must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 2001-NM-278-AD.” The postcard will be date stamped and returned to the commenter.
Availability of NPRMs
Any person may obtain a copy of this NPRM by submitting a request to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2001-NM-278-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.
The FAA has received a report of fatigue cracking of the station (STA) 340 upper deck floor beam on a Boeing Model 747-200F series airplane. The upper chord and web were completely severed by a crack which originated at a floor panel attachment fastener hole. A previous blend-out repair for corrosion was found at the crack location, and corrosion pitting was found in the fastener hole. Additionally, a 0.3-inch-long crack was found at an adjacent fastener hole. On certain Boeing Model 747-200C and -200F series airplanes, the upper chords of the floor beams at body station (BS) 340 through BS 440, and BS 500 through BS 520, are made from 7075 aluminum, which is more susceptible to fatigue cracking. BS 460 and BS 480 upper deck floor beams on these models are made from 2024 aluminum, which is known to be more durable than 7075 aluminum against fatigue. Cracking of the upper deck floor beam, if not corrected, could extend and sever floor beams adjacent to the body frame, which could result in rapid decompression and consequent loss of controllability of the airplane.
Other Relevant Rulemaking
On February 22, 2000, we issued AD 2000-04-17, amendment 39-11600 (65 FR 10695, February 29, 2000). That AD applies to certain Boeing Model 747-100, -200, and -300 series airplanes, and requires repetitive inspections to detect fatigue cracking in the upper deck floor beams located at certain body stations, and repair if necessary.
Explanation of Relevant Service Information
We have reviewed and approved Boeing Alert Service Bulletin 747-53A2439, dated July 5, 2001, which describes procedures for repetitive inspections to find fatigue cracking in the upper chord of the upper deck floor beams, and repair if necessary, as follows:
- If access is gained from above, the procedures specify an open-hole high frequency eddy current (HFEC) inspection of the attachment fastener holes of the floor panel for cracks in the upper chord.
- If access is gained from below, the procedures specify modification of the clip nuts of the attachment fastener holes of the floor panel, and surface HFEC inspections of the forward and aft horizontal flanges of the floor beam upper chord for cracks.
- If any crack is found, the procedures specify accomplishment of the repair in the service bulletin or contacting Boeing for repair instruction, and repetitive inspections of the repaired area. If no crack is found, repeat the applicable inspection.
The service bulletin also describes procedures for an optional repair/modification, which would extend certain repetitive inspection intervals.
Accomplishment of the actions specified in the service bulletin is intended to adequately address the identified unsafe condition.
Explanation of Requirements of Proposed Rule
Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, the proposed AD would require accomplishment of the actions specified in the service bulletin described previously, except as discussed below.
Difference Between the Alert Service Bulletin and This Proposed AD
Although the alert service bulletin specifies that the manufacturer may be contacted for disposition of certain repair conditions, this proposed AD would require the repair of those conditions to be accomplished in accordance with a method approved by the FAA, or in accordance with data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the FAA to make such findings.
Changes to 14 CFR Part 39/Effect on the Proposed AD
On July 10, 2002, the FAA issued a new version of 14 CFR part 39 (67 FR 47997, July 22, 2002), which governs the FAA's airworthiness directives system. The regulation now includes material that relates to altered products, special flight permits, and alternative methods of compliance. Because we have now included this material in part 39, we no longer need to include it in each individual AD; however, this AD identifies the office authorized to approve alternative methods of compliance.
There are approximately 78 airplanes of the affected design in the worldwide fleet. The FAA estimates that 21 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 30 work hours per airplane to accomplish the proposed inspections, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the inspections proposed by this AD on U.S. operators is estimated to be $37,800, or $1,800 per airplane, per inspection cycle.
The cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this proposed AD were not adopted. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions.
The regulations proposed herein would not have a substantial direct effect on the States, on the relationship between the national Government and the States, or on the distribution of power and responsibilities among the various levels of government. Therefore, it is determined that this proposal would not have federalism implications under Executive Order 13132.Start Printed Page 43690
For the reasons discussed above, I certify that this proposed regulation (1) is not a “significant regulatory action” under Executive Order 12866; (2) is not a “significant rule” under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) if promulgated, will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. A copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES.Start List of Subjects
List of Subjects in 14 CFR Part 39
- Air transportation
- Aviation safety
The Proposed Amendment
Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:Start Part
PART 39—AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
2. Section 39.13 is amended by adding the following new airworthiness directive:
Boeing: Docket 2001-NM-278-AD.
Applicability: Model 747-200C and -200F series airplanes, as listed in Boeing Alert Service Bulletin 747-53A2439, dated July 5, 2001; certificated in any category.
Compliance: Required as indicated, unless accomplished previously.
To find and fix cracking in certain upper deck floor beams, which could extend and sever floor beams adjacent to the body frame and could result in rapid decompression and consequent loss of controllability of the airplane, accomplish the following:
Inspections and Repair
(a) Before the accumulation of 22,000 total flight cycles, or within 1,000 flight cycles after the effective date of this AD, whichever is later: Do the applicable inspection to find fatigue cracking in the upper chord of the upper deck floor beams as specified in Part 1 (Open-Hole High Frequency Eddy Current (HFEC) Inspection Method) or Part 2 (Surface HFEC Inspection Method) of the Work Instructions of Boeing Alert Service Bulletin 747-53A2439, dated July 5, 2001. Do the inspections per the service bulletin.
(1) If any crack is found, before further flight, repair per Part 3 (Repair) of the Work Instructions of the service bulletin; except where the service bulletin specifies to contact Boeing for appropriate action, before further flight, repair according to a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA; or according to data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative (DER) who has been authorized by the Manager, Seattle ACO, to make such findings. For a repair method to be approved by the Manager, Seattle ACO, as required by this paragraph, the Manager's approval letter must specifically reference this AD. Do the applicable inspection of the repaired area per Part 1 of the service bulletin at the applicable time per Part 3 of the service bulletin. Repeat the applicable inspection at the applicable interval per Figure 1 of the service bulletin.
(2) If no crack is found, repeat the applicable inspection per paragraph (a) of this AD within the applicable interval per Figure 1 of the service bulletin. As an option, accomplishment of paragraph (b)(1) or (b)(2) of this AD, before further flight, extends the threshold for the initiation of the repetitive inspections required by this paragraph.
(b) For airplanes on which the inspection required by paragraph (a) of this AD is done per Part 1 of the Work Instructions of Boeing Alert Service Bulletin 747-53A2439, dated July 5, 2001; and on which no cracking is found: Accomplishment of the actions specified in either paragraph (b)(1) or (b)(2) of this AD extends the threshold for the initiation of the repetitive inspections required by paragraph (a)(2) of this AD.
(1) Do the repair per Part 3 of the service bulletin. At the applicable time specified in Table 1 of Part 3 of the service bulletin, do the inspection of the repaired area per Part 1 of the service bulletin. Repeat the inspection thereafter within the applicable interval per Figure 1 of the service bulletin.
(2) Do the modification of the attachment hole of the floor panel per Figure 5 of the service bulletin. Within 10,000 flight cycles after accomplishment of the modification, do the inspection of the modified area per Part 1 of the service bulletin. Repeat the inspection thereafter within the applicable interval per Figure 1 of the service bulletin.
Adjustments to Compliance Time: Cabin Differential Pressure
(c) For the purposes of calculating the compliance threshold and repetitive interval for the actions required by paragraph (a) of this AD: The number of flight cycles in which cabin differential pressure is at 2.0 pounds per square inch (psi) or less need not be counted when determining the number of flight cycles that have occurred on the airplane, provided that flight cycles with momentary spikes in cabin differential pressure above 2.0 psi are included as full pressure cycles. For this provision to apply, all cabin pressure records must be maintained for each airplane. No fleet-averaging of cabin pressure is allowed.
Alternative Methods of Compliance
(d)(1) In accordance with 14 CFR 39.19, the Manager, Seattle ACO, is authorized to approve alternative methods of compliance (AMOCs) for this AD.
(2) An AMOC that provides an acceptable level of safety may be used for any repair required by this AD, if it is approved by a Boeing Company DER who has been authorized by the Manager, Seattle ACO, to make such findings.
Issued in Renton, Washington, on July 18, 2003.
Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.
[FR Doc. 03-18788 Filed 7-23-03; 8:45 am]
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